The subject matter disclosed herein relates to gas turbine fuel systems and, more particularly, a method of purging a fluid supply line of a combustor.
Industrial gas turbine engines have fuel supply systems that require a liquid fuel purge system to clear the fuel nozzles in the combustors of liquid fuel. The liquid fuel purge system flushes out any remaining liquid fuel from nozzles of a combustor assembly with a flow of a fluid therethrough. As the purging fluid is routed through a fluid supply line of the liquid fuel purge system, multiple valves in series are manipulated to regulate the flow rate of the fluid therein. If the valves are opened and closed simultaneously or if an upstream control valve is opened before a downstream valve, the upstream valve may be set to a higher flow rate set point due to inherent dynamic response characteristics of the upstream valve. Such a condition may result in an overshoot of water to the nozzles.